Fuel cell manifold having embedded dielectric layer and methods of making the same

Abstract

To provide a fuel plenum for uniformly distributing fuel gas to each cell of a fuel cell stack.SOLUTION: A manifold plate 380 for a fuel cell stack includes a lower manifold portion, an upper manifold portion, a dielectric layer 364 sandwiched between the lower manifold portion and the upper manifold portion, a bottom inlet hole 384A and a bottom outlet hole formed in a bottom surface of the lower manifold portion, where the bottom inlet hole and the bottom outlet hole extend through the dielectric layer 364, top outlet holes 390B and top inlet holes 390A formed in opposing sides of a top surface of the upper manifold portion, outlet channels fluidly connecting the top outlet holes 390B to the bottom inlet hole 384A, and inlet channels fluidly connecting the top inlet holes 390A to the bottom outlet hole.SELECTED DRAWING: Figure 5A

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to fuel cell stacks and specifically to fuel cell manifolds. [Background technology]

[0002] In high-temperature fuel cell systems, such as solid oxide fuel cell (SOFC) systems, an oxidant stream passes through the cathode side of the fuel cell and a fuel stream passes through the anode side of the fuel cell. The oxidant stream is typically air, and the fuel stream can be a hydrocarbon fuel, such as methane, natural gas, pentane, ethanol, or methanol. The fuel cell operates at typical temperatures between 750°C and 950°C and allows the transfer of negatively charged oxygen ions from the cathode flow stream to the anode flow stream, where the ions combine with free hydrogen or hydrogen in hydrocarbon molecules to produce water vapor and / or with carbon monoxide to produce carbon dioxide. Excess electrons from the negatively charged ions are returned to the cathode side of the fuel cell via an electrical circuit completed between the anode and cathode, resulting in electrical current flowing through the circuit.

[0003] Fuel cell stacks can have internal or external fuel and air manifolds. In an internal manifold stack, fuel and air are distributed to each cell using risers contained within the stack. In other words, gas flows through openings or holes in the support layers of each fuel cell, such as the electrolyte layer, and through the gas flow separators of each cell. In an external manifold stack, the stack is open on the fuel and air inlet and outlet sides, and the fuel and air are introduced and withdrawn independently of the stack hardware. For example, the inlet and outlet fuel and air flow through separate passages between the stack and the manifold housing in which the stack is located.

[0004] Fuel cell stacks are often fabricated from multiple cells in the form of planar elements, tubes, or other geometries. Fuel and air must be supplied to electrochemically active surfaces, which can be large. One of the components of a fuel cell stack is a so-called gas flow separator (called a gas flow separator plate in a planar stack) that separates the individual cells in the stack. The gas flow separator plate separates the fuel, e.g., hydrogen or hydrocarbon fuel, flowing to the anode (i.e., the fuel electrode) of one cell in the stack from the oxidant, e.g., air, flowing to the cathode (i.e., the cathode) of an adjacent cell in the stack. In many cases, the gas flow separator plate also serves as an interconnect, electrically connecting the anode of one cell to the cathode of an adjacent cell. In this case, the gas flow separator plate, which functions as an interconnect, is made of or includes an electrically conductive material. Summary of the Invention

[0005] According to one embodiment, a manifold plate for a fuel cell stack includes a lower manifold section, an upper manifold section, and a dielectric layer sandwiched between the lower and upper manifold sections. The manifold plate may further include lower inlet and outlet holes formed in a lower surface of the lower manifold section and extending through the dielectric layer, and upper outlet and inlet holes formed on opposite sides of a top surface of the upper manifold section. The manifold plate may further include outlet passages fluidly connecting the upper outlet holes to the lower inlet holes and inlet passages fluidly connecting the upper inlet holes to the lower outlet holes.

[0006] According to another embodiment, a method of manufacturing a manifold plate for a fuel cell stack includes providing a lower manifold portion and an upper manifold portion, providing a dielectric layer, and assembling the lower manifold portion, the upper manifold portion, and the dielectric layer into a manifold plate such that the dielectric layer is sandwiched between the lower manifold portion and the upper manifold portion. [Brief explanation of the drawings]

[0007] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present disclosure and, together with the general description above and the detailed description below, serve to explain features of the disclosure. [Figure 1A] FIG. 1 is a perspective view of a conventional fuel cell column. [Figure 1B] FIG. 1B is a perspective view of one counterflow solid oxide fuel cell stack included in the column of FIG. 1A. [Figure 1C] FIG. 1C is a cross-sectional side view of a portion of the stack of FIG. 1B. [Figure 2A] FIG. 1C is a top view of the air side of a conventional interconnect of the stack of FIG. 1B. [Figure 2B] FIG. 1C is a top view of the fuel side of a conventional interconnect for the stack of FIG. 1B. [Figure 3A] 1 is a perspective view of a fuel cell stack according to various embodiments. [Figure 3B] 3B is an exploded perspective view of a portion of the stack of FIG. 3A according to various embodiments. [Figure 3C] FIG. 3B is a top view of the fuel side of an interconnect included in the stack of FIG. 3A according to various embodiments. [Figure 3D] 3B is a schematic diagram of a fuel cell included in the stack of FIG. 3A, according to various embodiments. [Figure 4A] FIG. 3D is a plan view of the air side of the cross-flow interconnect of FIG. 3C in accordance with various embodiments. [Figure 4B]FIG. 3D is a plan view of the fuel side of the cross-flow interconnect of FIG. 3C, according to various embodiments. [Figure 5A] FIG. 1 is an exploded top perspective view of a fuel flow structure according to various embodiments. [Figure 5B] FIG. 5B is an exploded bottom perspective view of the fuel flow structure of FIG. 5A according to various embodiments. [Figure 6A] 5A and 5B according to various embodiments. FIG. [Figure 6B] 6B is a cross-sectional view of the seal plate of FIG. 6A taken along line L3 shown in FIG. 6A, according to various embodiments. [Figure 7A] FIG. 5C is a bottom view of the manifold plate of the fuel flow structure of FIGS. 5A and 5B according to various embodiments. [Figure 7B] 7B is a cross-sectional view of the manifold plate of FIG. 7A taken along line L4 shown in FIG. 7A, according to various embodiments. [Figure 7C] 7B is a schematic top view of the manifold plate of FIG. 7A, according to various embodiments. [Figure 8A] FIG. 5C is a vertical cross-sectional view of the fuel flow structure of FIGS. 5A and 5B taken along line L1 in FIG. 5A, showing the assembled fuel plenum and inlet conduit according to various embodiments. [Figure 8B] FIG. 5C is a vertical cross-sectional view of the fuel flow structure of FIGS. 5A and 5B taken along line L2 in FIG. 5A, showing the assembled fuel plenum and outlet conduit according to various embodiments. [Figure 9AB] FIG. 9A is a top perspective view of a fuel cell manifold plate having an embedded dielectric layer according to various embodiments, and FIG. 9B is an exploded view of the fuel cell manifold plate of FIG. 9A according to various embodiments. [Figure 10A] 1A-1C illustrate intermediate structures used in forming a dielectric layer for a fuel cell manifold plate, according to various embodiments. [Figure 10B]10A-10C illustrate another intermediate structure used in forming a dielectric layer for a fuel cell manifold plate, according to various embodiments. [Figure 10C] 10A-10C illustrate another intermediate structure used in forming a dielectric layer for a fuel cell manifold plate, according to various embodiments. [Figure 10D] 1A-1C illustrate dielectric layers for fuel cell manifold plates according to various embodiments. [Figure 11] 9B is a cross-sectional view of the manifold plate of FIG. 9A taken along line L5 shown in FIG. 9A, according to various embodiments. [Figure 12A] 9A and 9B, including the manifold plate of FIG. 9B, according to various embodiments. [Figure 12B] 12B is a vertical cross-sectional view of the fuel flow structure of FIG. 12A according to various embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0008] Various embodiments will be described in detail with reference to the accompanying drawings. The drawings, which are not necessarily to scale, are intended to illustrate various features of the present disclosure. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References to specific examples and embodiments are for illustrative purposes only and are not intended to limit the scope of the disclosure or the claims.

[0009] Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, examples include from the one particular value and / or to the other particular value. Similarly, when values ​​are expressed as approximations, by immediately using "about" or "substantially," it will be understood that the particular value constitutes another embodiment. In some embodiments, a value of "about X" may include + / - 1% of the value of X. Additionally, it is understood that the endpoints of each range are significant both in relation to the other endpoint, and independently of the other endpoint.

[0010] FIG. 1A is a perspective view of a conventional fuel cell column 30, FIG. 1B is a perspective view of one counterflow SOFC stack 20 included in the column 30 of FIG. 1A, and FIG. 1C is a cross-sectional side view of a portion of the stack 20 of FIG. 1B.

[0011] 1A and 1B, a column 30 may include one or more stacks 20, a fuel inlet conduit 32, an anode exhaust conduit 34, and an anode feed / return assembly 36 (e.g., an anode splitter plate (ASP) 36). The column 30 may also include a side baffle 38 and a compression assembly 40. The side baffle 38 may be coupled to the compression assembly 40 and to a stack component (not shown) disposed below via a ceramic connector 39. The fuel inlet conduit 32 is fluidly connected to the ASPs 36 and configured to provide a fuel supply to each ASP 36, and the anode exhaust conduit 34 is fluidly connected to the ASPs 36 and configured to receive an anode fuel exhaust from each ASP 36.

[0012] The ASP 36 is disposed between the stacks 20 and is configured to provide a fuel supply including a hydrocarbon fuel to the stacks 20 and to receive an anode fuel exhaust from the stacks 20. For example, the ASP 36 may be fluidly connected to an internal fuel riser passage 22 formed within the stacks 20, as described below.

[0013] 1C, stack 20 includes multiple fuel cells 1 separated by interconnects 10, sometimes called gas flow separator plates or bipolar plates. Each fuel cell 1 includes a cathode electrode 3, a solid oxide electrolyte 5, and an anode electrode 7.

[0014] Each interconnect 10 electrically connects adjacent fuel cells 1 in the stack 20. In particular, an interconnect 10 can electrically connect the anode electrode 7 of one fuel cell 1 to the cathode electrode 3 of an adjacent fuel cell 1. FIG. 1C shows the lower fuel cell 1 positioned between two interconnects 10.

[0015] Each interconnect 10 includes ribs 12 that at least partially define fuel passages 8A and air passages 8B. The interconnects 10 can act as gas-fuel separators that separate fuel, e.g., a hydrocarbon fuel, flowing to the anode (i.e., anode 7) of one cell in the stack from oxidant, e.g., air, flowing to the cathode (i.e., cathode 3) of an adjacent cell in the stack. One end of the stack 20 may be provided with an air end plate or a fuel end plate (not shown) for supplying air or fuel, respectively, to the end electrodes.

[0016] Figure 2A is a plan view of the air side of a conventional interconnect 10, and Figure 2B is a plan view of the fuel side of the interconnect 10. With reference to Figures 1C and 2A, the air side includes air passages 8B. Air flows through the air passages 8B to the cathode electrodes 3 of adjacent fuel cells 1. In particular, air can flow across the interconnect 10 in a first direction A, as indicated by the arrows.

[0017] A ring seal 23 may surround the fuel holes 22A of the interconnect 10 to prevent fuel from contacting the cathode electrode. A band-like perimeter seal 24 is disposed around the perimeter of the air side of the interconnect 10. The seals 23, 24 may be formed from a glass material. The perimeter may be in the form of a flat portion of a raised area that does not include ribs or passages. The surface of the perimeter region may be flush with the tops of the ribs 12.

[0018] 1C and 2B, the fuel side of the interconnect 10 may include a fuel passage 8A and a fuel manifold 28 (e.g., a fuel plenum). Fuel flows from one of the fuel holes 22A into the adjacent manifold 28, through the fuel passage 8A, and to the anode 7 of the adjacent fuel cell 1. Excess fuel can flow into the other fuel manifold 28 and then into the adjacent fuel hole 22A. In particular, fuel can flow across the interconnect 10 in a second direction B, as indicated by the arrows. The second direction B may be perpendicular to the first direction A (see FIG. 2A).

[0019] A frame-like seal 26 is positioned in the peripheral region on the fuel side of the interconnect 10. The peripheral region may be a flat portion of the raised section that does not include ribs or passages. The surface of the peripheral region may be flush with the tops of the ribs 12.

[0020] Thus, conventional counterflow fuel cell columns such as those shown in Figures 1A, 1B, 1C, 2A, and 2B may include complex fuel distribution systems (fuel rails and anode splitter plates). Additionally, the use of internal fuel risers may require holes in the fuel cells and corresponding seals, thereby reducing the active area of ​​the fuel cells and potentially causing cracks in the ceramic electrolyte of the fuel cells 1.

[0021] The fuel manifold 28 may occupy a relatively large area of ​​the interconnect 10, which may reduce the contact area between the interconnect 10 and adjacent fuel cells by approximately 10%. Additionally, because the fuel manifold 28 is relatively deep, it represents a relatively thin region of the interconnect 10. Because the interconnect 10 is typically formed by a powder metallurgy compaction process, the density of the fuel manifold region may approach the theoretical density limit of the interconnect material. Therefore, the stroke length of the compaction press used in the compaction process is limited because the dense fuel manifold region cannot be further compacted. As a result, the compaction stroke limit may limit the density achieved in other locations of the interconnect 10 to a lower level. The resulting density variations may lead to localized variations, which may reduce the amount of contact between the interconnect 10 and the fuel cells 1 and reduce stack yield and / or performance.

[0022] Another important consideration in the design of fuel cell systems is the area of ​​operational efficiency. Maximizing fuel utilization is a key factor in achieving operational efficiency. Fuel utilization is the ratio of the amount of fuel consumed during operation to the amount of fuel supplied to the fuel cell. A key factor in maintaining the cycle life of a fuel cell can be avoiding fuel starvation in the active area of ​​the fuel cell by properly distributing the fuel across the active area. Uneven fuel distribution, such that some flow field passages do not receive enough fuel to support the electrochemical reactions occurring in that passage's area, can result in fuel starvation in the adjacent fuel cell region. To achieve more uniform fuel distribution, conventional interconnect designs include variations in passage depth across the entire flow field. This not only introduces complexity into the manufacturing process but can also require complex metrology to accurately measure these dimensions. The distribution of fuel through fuel holes and distribution manifolds can constrain various passage geometries.

[0023] One possible solution to this complex geometry and fuel manifolds is to have wider fuel openings to ensure more uniform fuel distribution throughout the fuel flow range. Because the formation of fuel manifolds contributes to density variations, eliminating the fuel manifolds should allow for more uniform density and permeability in the interconnect. Therefore, there is a need for an improved interconnect that provides uniform contact with the fuel cell while distributing fuel uniformly to the fuel cell without the use of traditional fuel manifolds.

[0024] Due to the overall constraints on scaling the size of the hot box of a fuel cell system, there is also a need for improved interconnects designed to maximize fuel utilization and fuel cell active area without increasing the hot box footprint.

[0025] FIG. 3A is a perspective view of a fuel cell stack 300 according to various embodiments, FIG. 3B is an exploded perspective view of a portion of the stack 300 of FIG. 3A, FIG. 3C is a top view of the fuel side of an interconnect 400 included in the stack 300, and FIG. 3D is a schematic diagram of a fuel cell included in the stack 300.

[0026] 3A-3D, a fuel cell stack 300, which does not have an ASP and therefore may also be referred to as a fuel cell column, includes multiple fuel cells 310 separated by interconnects 400, which may also be referred to as gas flow separator plates or bipolar plates. One or more stacks 300 may be thermally integrated with other components of the fuel cell power generation system (e.g., one or more anode exhaust gas oxidizers, fuel reformers, fluid conduits and manifolds, etc.) within a common enclosure or "hot box."

[0027] The interconnect 400 is fabricated from an electrically conductive metallic material. For example, the interconnect 400 may include a chromium alloy, such as a Cr—Fe alloy. The interconnect 400 is typically fabricated using powder metallurgy techniques, including pressing and sintering a Cr—Fe powder, which may be a mixture of Cr and Fe powders or a Cr—Fe alloy powder, to form a Cr—Fe interconnect of a desired size and shape (e.g., a “net shape” or “near net shape” process). A typical chromium alloy interconnect 400 includes greater than about 90% chromium by weight, such as about 94-96% (e.g., 95%) chromium by weight. The interconnect 400 may also include less than about 10% iron by weight, such as about 4-6% (e.g., 5%) iron by weight, less than about 2% by weight, such as about 0-1% by weight, of other materials, such as yttrium or yttria, and residual or unavoidable impurities.

[0028] Each fuel cell 310 may include a solid oxide electrolyte 312, an anode 314, and a cathode 316. In some embodiments, the anode 314 and cathode 316 can be printed on the electrolyte 312. In other embodiments, a conductive layer 318, such as a nickel mesh, may be disposed between the anode 314 and the adjacent interconnect 400. The fuel cell 310 does not include through-holes, such as the fuel holes of conventional fuel cells. Thus, the fuel cell 310 avoids cracks that can occur due to the presence of such through-holes.

[0029] The top and bottom interconnects 400 of the stack 300 may be differently configured air-side or fuel-side end plates, each with features for providing air or fuel to the adjacent end fuel cells 310. As used herein, "interconnect" can refer to either an interconnect disposed between two fuel cells 310 or an end plate disposed at the end of the stack and directly adjacent to only one fuel cell 310. Because the stack 300 does not include an ASP and its associated end plate, the stack 300 may include only two end plates. As a result, the dimensional variations in the stack associated with the use of intra-column ASP can be avoided.

[0030] The stack 300 may include a side baffle 302, a fuel plenum 350, and a compression assembly 306. The side baffles 302 may be formed of a ceramic material and may be positioned on opposite sides of the fuel cell stack 300, which includes stacked fuel cells 310 and interconnects 400. The side baffles 302 may connect the fuel plenum 350 and the compression assembly 306 so that the compression assembly 306 can apply pressure to the stack 300. The side baffles 302 may be curved baffle plates, each covering at least a portion of three sides of the fuel cell stack 300. For example, one baffle plate may completely cover the fuel inlet riser side of the stack 300 and partially cover the adjacent front and back sides of the stack, while the other baffle plate completely covers the fuel outlet riser side of the stack and partially covers adjacent portions of the front and back sides of the stack. The remaining uncovered portions of the top and back sides of the stack allow air to flow through the stack 300. The curved baffle plate improves control of airflow through the stack compared to a conventional baffle plate 38 that covers only one side of the stack. A fuel plenum 350 may be disposed below the stack 300 and may be configured to provide a hydrogen-containing fuel supply to the stack 300 and may receive an anode fuel exhaust from the stack 300. The fuel plenum 350 may be connected to a fuel inlet and outlet conduit 320 disposed below the fuel plenum 350.

[0031] Each interconnect 400 electrically connects adjacent fuel cells 310 in the stack 300. In particular, the interconnect 400 can electrically connect the anode electrode of one fuel cell 310 to the cathode electrode of an adjacent fuel cell 310. As shown in FIG. 3C , each interconnect 400 can be configured to allow air to flow in a first direction A to provide air to the cathode of the adjacent fuel cell 310. Each interconnect 400 can also be configured to allow fuel to flow in a second direction F to provide fuel to the anode of the adjacent fuel cell 310. The directions A and F can be perpendicular or substantially perpendicular to each other. Thus, the interconnect 400 can be referred to as a cross-flow interconnect.

[0032] The interconnect 400 may include fuel holes extending therethrough and configured for fuel distribution. For example, the fuel holes may include one or more fuel inlets 402 and one or more fuel (e.g., anode exhaust) outlets 404, which may also be referred to as anode exhaust outlets 404. The fuel inlets 402 and fuel outlets 404 may be located outside the periphery of the fuel cell 310. Thus, the fuel cell 310 may be formed without corresponding through-holes for fuel flow. The combined length of the fuel inlets 402 and / or the combined length of the fuel outlets 404 may be at least 75% of the corresponding length of the interconnect 400, e.g., the length in direction A.

[0033] 3B, each interconnect 400 includes two fuel inlets 402 separated by a neck portion 412 of the interconnect 400. However, more than two fuel inlets 402 may be included, for example, three to five inlets separated by two to four neck portions 412. In one embodiment, as shown in FIG. 3B, each interconnect 400 includes two fuel outlets 404 separated by a neck portion 414 of the interconnect 400. However, more than two fuel outlets 404 may be included, for example, three to five outlets separated by two to four neck portions 414.

[0034] The fuel inlets 402 of adjacent interconnects 400 may be aligned within the stack 300 to form one or more fuel inlet risers 403. The fuel outlets 404 of adjacent interconnects 400 may be aligned within the stack 300 to form one or more fuel outlet risers 405. The fuel inlet risers 403 may be configured to distribute fuel received from the fuel plenum 350 to the fuel cells 310. The fuel outlet risers 405 may be configured to provide anode exhaust received from the fuel cells 310 to the fuel plenum 350.

[0035] Unlike the flat side baffles 38 of the related art shown in Figure 1A, the side baffles 302 may be curved to surround the edges of the interconnect 400. In particular, the side baffles 302 may be positioned to surround the fuel inlet 402 and the fuel outlet 404 of the interconnect 400. Thus, the side baffles may more efficiently control airflow through the air passages of the interconnect 400 that are exposed between the side baffles 302 and are described in detail with respect to Figures 4A and 4B.

[0036] In various embodiments, stack 300 may include at least 30, at least 40, at least 50, or at least 60 fuel cells, which may be provided with fuel using only fuel risers 403, 405. In other words, compared to conventional fuel cell systems, the crossflow configuration may provide fuel to a large number of fuel cells without the need for external fuel manifolds, such as external conduits 32, 34, of the ASP or stack shown in FIG.

[0037] Each interconnect 400 may be made of or include a conductive material, such as a metal alloy (e.g., a chromium-iron alloy) having a thermal expansion coefficient similar to that of the cell's solid oxide electrolyte (e.g., a difference of 0-10%). For example, the interconnect 400 may include a metal (e.g., a chromium-iron alloy, such as 4-6% by weight iron, optionally 1% by weight or less yttrium and the balance chromium alloy) and may electrically connect the anode side, i.e., fuel side, of a given fuel cell 310 with the cathode side, i.e., air side, of an adjacent fuel cell 310. A conductive contact layer, such as a nickel contact layer (e.g., a nickel mesh), may be provided between the anode and each interconnect 400. Another optional conductive contact layer may be provided between the cathode electrode and each interconnect 400.

[0038] Surfaces of the interconnect 400 that are exposed to an oxidizing environment (e.g., air) during operation, such as the cathode-facing side of the interconnect 400, may be coated with a protective coating layer to reduce the growth rate of the interconnect's chromium oxide surface layer and inhibit the evaporation of chromium vapor species that would otherwise degrade the fuel cell cathode. Typically, the coating layer, which may include a perovskite, e.g., LSM, may be formed using a thermal spray coating or dip coating process. Alternatively, other metal oxide coatings, such as spinels, e.g., (Mn,Co)3O4 spinel (MCO), may be used instead of or in addition to LSM. Mn 2-x Co 1+xAny spinel having a composition written as O4 (0≦x≦1), or z(Mn3O4)+(1−z)(Co3O4), where (1 / 3≦z≦2 / 3), or written as (Mn,Co)3O4, can be used. In other embodiments, a mixed layer of LSM and MCO or a stack of LSM and MCO layers may be used as the coating layer.

[0039] 4A and 4B are plan views illustrating the air side and fuel side, respectively, of a cross-flow interconnect 400 according to various embodiments. Referring to FIG. 4A, the air side of the interconnect 400 may include ribs 406 configured to at least partially define air passages 408 configured to provide air to the cathodes of the attached fuel cells 310. The air side of the interconnect 400 may be divided into an air flow area 420 including the air passages 408 and riser sealing surfaces 422 disposed on two opposite sides of the air flow area 420. One of the riser sealing surfaces 422 may surround the fuel inlet 402, and the other riser sealing surface 422 may surround the fuel outlet 404. The air passages 408 and ribs 406 may extend completely across the air side of the interconnect 400 such that the air passages 408 and ribs 406 terminate at opposite peripheries of the interconnect 400. In other words, when assembled into stack 300, opposite ends of air passages 408 and ribs 406 are positioned on opposite exterior (e.g., top and bottom) surfaces of the stack, allowing blown air to flow through the stack. Thus, the stack may be provided with an external air manifold.

[0040] Riser seals 424 may be disposed on the riser seal surface 422. For example, one riser seal 424 may surround the fuel inlet 402 and one riser seal 424 may surround the fuel outlet 404. The riser seals 424 may prevent fuel and / or anode exhaust from entering the air flow area 420 and contacting the cathodes of the fuel cells 310. The riser seals 424 may also function to prevent fuel from leaking out of the fuel cell stack 100 (see FIG. 3A).

[0041] 4B , the fuel side of the interconnect 400 may include ribs 416 that at least partially define fuel passages 418 configured to provide fuel to the anodes of the mounted fuel cells 310. The fuel side of the interconnect 400 may be divided into a fuel flow area 430 that includes the fuel passages 418 and a peripheral sealing surface 432 that surrounds the fuel flow area 430 and the fuel inlets 402 and fuel outlets 404. The ribs 416 and fuel passages 418 may extend in a direction that is orthogonal or substantially orthogonal to the direction in which the air-side passages 408 and ribs 406 extend.

[0042] A frame-shaped perimeter seal 434 may be disposed on the perimeter sealing surface 432. The perimeter seal 434 may be configured to prevent air from entering the fuel flow area 430 and contacting the anodes of adjacent fuel cells 310. The perimeter seal 434 may also function to prevent fuel from exiting the fuel risers 403, 405 and leaking out of the fuel cell stack 300 (see FIGS. 3A and 3B).

[0043] The seals 424, 434 may include a glass or ceramic seal material. The seal material may have low electrical conductivity. In some embodiments, the seals 424, 434 may be formed by printing one or more layers of the seal material onto the interconnect 400 and then sintering.

[0044] As shown in FIG. 1A , in conventional fuel cell systems, fuel is provided to and fuel exhaust is received from a fuel cell stack via a metal anode splitter plate 36. The anode splitter plates 36 are fluidly connected to one another via a fuel inlet conduit 32 and an anode exhaust conduit 34. The conduits 32 and 34 include metal tubes welded to the anode splitter plate 36 and to a ceramic component that serves as a dielectric breakdown means. Thus, fluid connection between the anode splitter plates 36 relies on expensive dielectric components and a significant amount of on-site welding. Therefore, a more cost-effective method for providing fuel to and receiving fuel exhaust from a fuel cell stack is needed.

[0045] Figure 5A is an exploded top perspective view of a fuel flow structure 500 according to various embodiments of the present disclosure, and Figure 5B is an exploded bottom perspective view of the fuel flow structure 500 of Figure 5A. Referring to Figures 5A and 5B, the fuel flow structure 500 includes a fuel conduit 320 and a fuel plenum 350. The fuel plenum 350 may include a seal ring 354, a glass or glass-ceramic seal 356, a base plate 360, a dielectric layer 364, a cover plate 366, a seal plate 370, and a manifold plate 380.

[0046] The fuel plenum 350 may be configured to form a fluid-tight connection with the fuel conduit 320. The fuel conduit 320 may include an inlet conduit 320A configured to provide fuel to the fuel plenum 350 and an outlet conduit 320B configured to receive fuel exhaust from the fuel plenum 350. The fuel conduit 320 may include a metal tube 322, a metal bellows 324, and a dielectric ring 326. The metal tube 322 may be coupled to the bellows 324 and the dielectric ring 326 by, for example, brazing, welding, or a press fit. The bellows 324 may operate to compensate for differences in thermal expansion coefficients between the fuel cell components by deforming and absorbing stress. In an alternative embodiment, rather than being coupled to the bellows 324, the metal tube 322 may itself be entirely comprised of or fabricated from the bellows, such that the metal tube / bellows 322 may be directly coupled to the dielectric ring 326. The dielectric ring 326 can act as a dielectric breakdown means to prevent electrical current from being guided through the fuel conduit 320 and electrically shorting out the fuel cell stack disposed above the fuel plenum 350 .

[0047] The base plate 360, the dielectric layer 364, and the cover plate 366 may each have inlet holes 361A, 365A, and 367A and outlet holes 361B, 365B, and 367B, which may be through-holes extending through the respective plates and layers. The base plate 360 ​​may have a plurality of protrusions 362 configured to mate with the ceramic connector 39 shown in FIG. 1A. The base plate 360 ​​and the cover plate 366 may be formed of a densified dielectric material. For example, the base plate 360 ​​and the cover plate 366 may be formed of a substantially non-porous, electrically insulating ceramic material, such as alumina, zirconia, yttria-stabilized zirconia (YSZ) (e.g., 3% yttria-stabilized zirconia), or the like. The base plate 360 ​​and the cover plate 366 may be rigid plates configured to provide support for the dielectric layer 364.

[0048] In some embodiments, dielectric layer 364 may be formed of a ceramic material having a higher dielectric constant than the ceramic material of base plate 360 ​​and / or cover plate 366. In other words, dielectric layer 364 may be able to withstand a higher maximum electric field (i.e., have a higher breakdown voltage) without breaking down and becoming conductive than base plate 360 ​​and cover plate 366. For example, dielectric layer 364 may be formed of one or more layers of porous ceramic yarn or fabric that has high electrical insulation at high temperatures, such as Nextel Ceramic Fabric Nos. 312, 440, or 610, available from 3M Company.

[0049] In another embodiment, the dielectric layer 364 may be formed of a ceramic matrix composite (CMC) or any comparable material that has a high dielectric strength due to a high surface area to volume ratio. The CMC may include, for example, an aluminum oxide (e.g., alumina), zirconium oxide, or silicon carbide matrix. Other matrix materials may be selected as well. The fibers may be made of alumina, carbon, silicon carbide, or any other suitable material. In one embodiment, both the matrix and the fibers may include alumina. Thus, the dielectric layer 364 may be configured to act as a dielectric breakdown means to prevent electrical conduction through the fuel plenum 350.

[0050] The cover plate 366 and the base plate 360 ​​may have a higher density than the dielectric layer 364. For example, the cover plate 366 and / or the base plate 360 ​​may be formed of a sufficiently dense ceramic material, such as 97% to 99.5% high-density alumina. The cover plate 366 is configured to isolate the seal plate 370 from the dielectric layer 364. In this manner, the cover plate 366 may be configured to prevent diffusion of metal species from the seal plate 370 into the dielectric layer 364. For example, the cover plate 366 may reduce and / or prevent diffusion of chromium species (e.g., chromium oxide) from the seal plate 370 into the dielectric layer 364, thereby preventing the chromium species from reducing the dielectric strength and / or otherwise reducing the structural integrity of the dielectric layer 364.

[0051] The seal plate 370 and the manifold plate 380 may be formed from a metal or metal alloy, such as stainless steel, that can be easily welded to the fuel conduits 320. For example, the seal plate 370 and / or the manifold plate 380 may be formed from 446 stainless steel, etc. 446 stainless steel contains 23-27% by weight Cr, up to 1.5% by weight Mn, up to 1% by weight of one or more of Si, Ni, C, P, and / or S, and the balance Fe. In some embodiments, the seal plate 370 and / or the manifold plate 380 may be formed by brazing together multiple metal subplates. In embodiments formed using metal subplates, the subplates may be cut to form various structures, such as holes and / or passages, before or after the brazing process. In some embodiments, laser cutting or the like may be used to cut such structures.

[0052] The seal plate 370 and the manifold plate 380 may each have a coating 372, 382 on one or both sides, e.g., at least on the surfaces of the plates 370, 380 that face each other. The coatings 372, 382 may have a thickness ranging from about 75 μm to about 200 μm, e.g., from about 100 μm to about 175 μm, from about 110 μm to about 140 μm, or about 120 μm. Typically, the coatings 372, 382 may include a metal oxide material, e.g., a perovskite material, e.g., lanthanum strontium manganite (LSM). Alternatively, another metal oxide coating, e.g., a spinel, e.g., (Mn,Co)3O4 spinel (MCO), may be used instead of or in addition to the LSM. Any spinel having the composition Mn2-xCo1+xO4(0□x□1), or written as z(Mn3O4)+(1-z)(Co3O4), which is (1 / 3□z□2 / 3), or written as (Mn,Co)3O4, may be used. In another embodiment, mixed layers of LSM and MCO, or stacks of LSM and MCO layers, may be used as coatings 372, 382. Coatings 372, 382 may be formed using a thermal spray coating process or a dip coating process and applied to substantially all exterior surfaces of seal plate 370 and manifold plate 380.

[0053] The seal plate 370 may have inlet holes 374A and outlet holes 374B, which may be through-holes extending between the upper and lower surfaces of the seal plate 370. The manifold plate 380 may have lower inlet holes 384A and lower outlet holes 384B formed in the lower surface of the manifold plate 380 and upper inlet holes 390A and upper outlet holes 390B formed in the upper surface of the manifold plate 380 on opposite sides of the manifold plate 380. While three upper inlet holes 390A and three upper outlet holes 390B are illustrated, the present disclosure is not limited to any particular number of upper inlet holes 390A and upper outlet holes 390B. For example, the manifold plate 380 may have two, four, five or more upper inlet holes 390A and two, four, five or more upper outlet holes 390B, depending on the number of fuel inlets and fuel outlets included in the corresponding fuel cell stack interconnect 400. For example, if the interconnect has three inlets and three outlets, the manifold plate 380 has three inlet holes 390A and three outlet holes 390B.

[0054] Base plate 360, dielectric layer 364, cover plate 366, seal plate 370, and manifold plate 380 may be laminated together such that inlet holes 361A, 365A, 367A, 374A, and 384A are aligned to form an inlet conduit passage 352A, and outlet holes 361B, 365B, 367B, 374B, and 384B are aligned to form an outlet conduit passage 352B. Inlet conduit 320A and outlet conduit 320B may be inserted into inlet conduit passage 352A and outlet conduit passage 352B, respectively, such that ends 328 of inlet conduit 320A and outlet conduit 320B may extend to and / or beyond the top surface of seal plate 370.

[0055] Figure 6A is a top view of seal plate 370, and Figure 6B is a cross-sectional view taken along line L3 in Figure 6A. Inlet seal area 378A and outlet seal area 378B may be formed around inlet hole 374A and outlet hole 374B in areas where coating 372 is not applied to the top surface of seal plate 370. In this manner, inlet seal area 378A and outlet seal area 378B may have a depth D2 equal to the thickness of coating 372, for example, a depth D2 of approximately 120 μm.

[0056] Figure 7A is a bottom view of manifold plate 380, Figure 7B is a cross-sectional view taken along line L4 in Figure 7A, and Figure 7C is a top view schematically illustrating manifold plate 380 according to various embodiments of the present disclosure. With reference to Figures 7A-7C, the bottom surface of manifold plate 380 may be formed with inlet recesses 386A and outlet recesses 386B surrounding lower inlet holes 384A and lower outlet holes 384B, respectively. Inlet recesses 386A and outlet recesses 386B may have a depth D3 ranging from about 0.5 mm to about 6 mm, for example, from about 1 cm to about 3 cm, for example, from about 0.5 cm to about 2 cm, or about 1 cm.

[0057] Inlet seal areas 388A and outlet seal areas 388B may be formed around inlet recess 386A and outlet recess 386B, respectively, in areas where coating 382 is not applied to the underside of manifold plate 380. In this manner, inlet seal area 388A and outlet seal area 388B may have a depth D4 equal to the thickness of coating 382, ​​for example, a depth D4 of about 120 μm.

[0058] The manifold plate 380 may have a plurality of internal inlet passages 392A and internal outlet passages 392B. The inlet passages 392A may fluidly connect the lower inlet holes 384A to each of the upper inlet holes 390A. The outlet passages 392B may fluidly connect the lower outlet holes 384B to each of the upper outlet holes 390B. The inlet passages 392A may be configured to provide substantially equal amounts of fuel (e.g., equal flow rates) from the common lower inlet holes 384A to each of the upper inlet holes 390A. The outlet passages 392B may be configured to provide substantially equal amounts of fuel exhaust from each of the upper outlet holes 390B to the common lower outlet hole 384B.

[0059] Additionally, manifold plate 380 may have electrical contacts 381. Manifold plate 380 may be electrically connected to the bottom of the fuel cell stack, and electrical contacts 381 may extend laterally from manifold plate 380 and may be configured to provide connection points for connecting manifold plate 380 to a current collection circuit.

[0060] FIG. 8A is a vertical cross-sectional view taken along line L1 of FIG. 5A showing the assembled fuel plenum 350 and inlet conduit 320A, and FIG. 8B is a vertical cross-sectional view taken along line L2 of FIG. 5A showing the assembled fuel plenum 350 and outlet conduit 320B.

[0061] 5A, 5B, 8A, and 8B, a base plate 360, a dielectric layer 364, a cover plate 366, a seal plate 370, and a manifold plate 380 are stacked together to form an inlet conduit passage 352A and an outlet conduit passage 352B. The inlet conduit 320A can be inserted into the inlet conduit passage 352A toward the lower inlet hole 384A. The outlet conduit 320B can be inserted into the outlet conduit passage 352B toward the lower outlet hole 384B.

[0062] A first seal ring 354A may be disposed around the inlet conduit 320A within the inlet recess 386A in the underside of the manifold plate 380. A second seal ring 354B may be disposed around the outlet conduit 320B within the outlet recess 386B in the underside of the manifold plate 380. The inlet conduit 320A and the outlet conduit 320B may be welded to the seal plate 370. In particular, the welding process may include welding the first seal ring 354A and the second seal ring 354B to the inlet conduit 320A and the outlet conduit 320B and to the surface of the seal plate 370, thereby ensuring a fluid-tight seal is formed between the inlet conduit 320A, the outlet conduit 320B, and the seal plate 370.

[0063] A first glass or glass ceramic seal 356A may be disposed in the inlet seal area 378A of the seal plate 370, and a second glass or glass ceramic seal 356B may be disposed in the inlet seal area 388A of the manifold plate 380. A third glass or glass ceramic seal 356C may be disposed in the outlet seal area 378B of the seal plate 370, and a fourth glass or glass ceramic seal 356D may be disposed in the outlet seal area 388B of the manifold plate 380, although in other embodiments a single glass or glass ceramic seal may be used. The seals 356A-356D may be heated to soften them, thereby forming a fluid-tight bond that physically couples the seal plate 370 to the manifold plate 380.

[0064] The entrance seal areas 378A and 388A may overlap to form a single entrance seal area 358A, and the exit seal areas 378B and 388B may overlap to form a single exit seal area 358B. The first seal 356A and the second seal 356B may be laminated to one another within the entrance seal area 358A, and the third seal 356C and the fourth seal 356D may be laminated to one another within the exit seal area 358B. The coatings 372 and 382 may be laminated to one another. As such, the height of the entrance seal area 358A and the exit seal area 358B may be equal to the combined thickness of the coatings 372 and 382.

[0065] The inlet seal area 358A and the outlet seal area 358B can provide space for the glass or glass-ceramic seals 356A-356D to expand laterally when heated to fuel cell system operating temperatures, thereby reducing stress on the glass or glass-ceramic seals 356A-356D over time. Additionally, because the seal plate 370 and the manifold plate 380 can be formed from the same material, the seal plate 370 and the manifold plate 380 can have matched coefficients of thermal expansion (CTE). Therefore, stress on the glass or glass-ceramic seals 356A-356D over time can be further reduced.

[0066] The glass or glass-ceramic seals 356A-356D may be formed of a high temperature glass or glass-ceramic material, such as a silicate or aluminosilicate glass or glass-ceramic material. In some embodiments, the glass or glass-ceramic seals 356A-356B may be formed of a silicate glass or glass-ceramic sealing material including SiO, BaO, CaO, AlO, KO, and / or BO. For example, the sealant may include SiO in an amount ranging from about 40% to about 60% by weight, e.g., from about 45% to about 55% by weight, BaO in an amount ranging from about 10% to about 35% by weight, e.g., from about 15% to about 30% by weight, CaO in an amount ranging from about 5% to about 20% by weight, e.g., from about 7% to about 16% by weight, AlO in an amount ranging from about 10% to about 20% by weight, e.g., from about 13% to about 15% by weight, and BO in an amount ranging from about 0.25% to about 7% by weight, e.g., from about 0.5% to about 5.5% by weight. In some embodiments, the sealant may additionally include KO in an amount ranging from about 0.5% to about 1.5% by weight, e.g., from about 0.75% to about 1.25% by weight.

[0067] In some embodiments, the glass or glass-ceramic seals 356A-356D may be formed of a silicate glass or glass-ceramic sealing material including SiO 2 , B 2 O 3 , Al 2 O 3 , CaO, MgO, La 2 O 3 , BaO, and / or SrO. For example, the sealing material may include SiO in an amount ranging from about 30 wt% to about 60 wt%, e.g., from about 35 wt% to about 55 wt%, BO in an amount ranging from about 0.5 wt% to about 15 wt%, e.g., from about 1 wt% to about 12 wt%, AlO in an amount ranging from about 0.5 wt% to about 5 wt%, e.g., from about 1 wt% to about 4 wt%, CaO in an amount ranging from about 2 wt% to about 30 wt%, e.g., from about 5 wt% to about 25 wt%, MgO in an amount ranging from about 2 wt% to about 25 wt%, e.g., from about 5 wt% to about 20 wt%, and LaO in an amount ranging from about 2 wt% to about 12 wt%, e.g., from about 5 wt% to about 10 wt%. In some embodiments, the sealant may additionally include BaO in an amount ranging from about 0 wt. % to about 35 wt. %, e.g., from about 0 wt. % to about 30 wt. %, or from about 0.5 wt. % to about 30 wt. %, including about 20 wt. % to about 30 wt. %, and / or SrO in an amount ranging from about 0 wt. % to about 20 wt. %, e.g., from about 0 wt. % to about 15 wt. %, or from about 0.5 wt. % to about 15 wt. %, including about 10 wt. % to about 15 wt. %. In some embodiments, the sealant may additionally include at least one of BaO and / or SrO in a non-zero amount, e.g., at least 0.5 wt. %, or both BaO and SrO in a non-zero amount, e.g., at least 0.5 wt. %, although other suitable sealants may be used.

[0068] When assembled into a fuel cell stack, such as the fuel cell stack 300 of Figures 3A-3C, the top inlet hole 390A may be fluidly connected to a fuel inlet 402 of an interconnect 400 of the stack 300, and the top outlet hole 390B may be fluidly connected to a fuel outlet 404 of the interconnect 400 as shown in Figure 4A. To provide a fluid-tight connection, for example, a glass or glass-ceramic seal 424 may be disposed between the top inlet hole 390A and the fuel inlet 402 of the adjacent interconnect 400, and a glass or glass-ceramic seal 424 may be disposed between the top outlet hole 390B and the fuel outlet 404 of the adjacent interconnect 400.

[0069] Figure 9A is a top perspective view of a fuel cell manifold plate 380 having an embedded dielectric layer 396, according to various embodiments, and Figure 9B is an exploded view of the fuel cell manifold plate 380 of Figure 9A, according to various embodiments. The presence of the dielectric layer 396 can reduce leakage current through the fuel cell manifold plate 380, which in turn can act to reduce corrosion of the manifold plate 380 and other structures. The dielectric layer 396 can also prevent shorting connections that could otherwise cause system malfunction and / or damage to system components.

[0070] As shown in FIG. 9B , the fuel cell manifold plate 380 may include an upper manifold portion 380a and a lower manifold portion 308b. The dielectric layer 396 may include a first dielectric layer portion 396a and a second dielectric layer portion 396b. As shown, the dielectric layer 396 may be divided along a dividing line 396c. The presence of the dividing line 396 may reduce thermal stresses / strains induced in the dielectric layer 396 based on the difference in CTE of the dielectric layer 396 relative to the CTEs of the upper manifold portion 380a and the lower manifold portion 308b. The fuel cell manifold plate 380 may further include seals 398 disposed above and below the dielectric layer 396, as shown in FIG. 9B . The seals 398 may include an electrically insulating material (e.g., glass or glass-ceramic) and may have a ring-shaped (i.e., “donut-shaped”) geometry. In alternative embodiments, seal 398 may have other shapes and may include other materials. Seal 398 extends through lower manifold portion 380b and surrounds lower inlet hole 384A and lower outlet hole 384B, which extend through first and second dielectric layer portions 396a and 396b, respectively. Seal 398 may prevent fuel and / or air leakage between upper manifold portion 380a, lower manifold portion 308b, and dielectric layer 396.

[0071] 10A-10C illustrate intermediate structures used in forming the dielectric layer 396 of FIG. 9B according to various embodiments, and FIG. 10D illustrates the dielectric layer 396 according to various embodiments. The intermediate structures of FIGS. 10A-10C illustrate the formation of one of the first and second dielectric layer portions 396a and 396b. The intermediate structure of FIG. 10A may be formed by placing an electrically insulating seal 1006 on a first dielectric shim 1002a. For example, the seal 1006 may include an insulating (e.g., glass or glass-ceramic) material and may have a ring-shaped (i.e., "donut-shaped") geometry. In alternative embodiments, the seal 1006 may have other shapes and may include other materials. The first shim 1002a may include a first hole 1004f configured to form a portion of one of the inlet conduit passage 352A and the outlet conduit passage 352B, as described above. For example, the first hole 1004f may include an upper portion of the lower inlet hole 384A or the lower outlet hole 384B described above.

[0072] In one exemplary embodiment, the first dielectric shim 1002a may include a ceramic material, such as alumina. In another embodiment, the first dielectric shim 1002a may include other materials. The first dielectric shim 1002a may have a thickness of 0.5 mm to 5 mm, for example, 2 mm to 3 mm. The intermediate structure of FIG. 10B may be formed by placing a cloth 1008 on the first dielectric shim 1002a. The cloth 1008 may include an insulating material that is stable at high temperatures. For example, the cloth 1008 may include glass fiber. The cloth may have a thickness of 0.25 mm to 1 mm, for example, approximately 0.5 mm. In another embodiment, the cloth 1008 may include other materials and have other thicknesses. The cloth 1008 is cut to the shape of the first dielectric shim 1002a, such that the second holes 1004s also extend through the cloth 1008. The fabric 1008 is disposed around the seal 1006 such that the second hole 1004s of the fabric 1008 is aligned with the seal 1006 and the first retention 1004f.

[0073] The intermediate structure of FIG. 10C can be formed by placing a second dielectric shim 1002b on the fabric 1008. In one exemplary embodiment, the second dielectric shim 1002b can include a ceramic material, such as alumina. In another embodiment, the second dielectric shim 1002b can include other materials. The second shim 102b can have the same or a different thickness as the first shim 102a. For example, the first shim 1002a and the second shim 1002b can each have a thickness of approximately 2 mm. In another embodiment, the first shim 1002a and the second shim 1002b can have other thicknesses. A third hole 1004t extends through the second shim 1002b.

[0074] According to one embodiment, the intermediate structure of FIG. 10C is then sintered under mechanical load at 800°C to 1200°C, e.g., 1000°C, at a rate of 1°C / min to 5°C / min, e.g., 2°C / min, soaked for a minimum of 3 hours, e.g., 3 to 10 hours, and cooled to room temperature at a rate of 1°C / min to 5°C / min, e.g., 2°C / min, to form an airtight sandwich assembly. In other embodiments, the intermediate structure of FIG. 10C can be processed in other ways. The resulting airtight sandwich assembly can form one of the first dielectric layer portion 396a and the second dielectric layer portion 396b of the dielectric layer 396.

[0075] As shown in FIG. 10D , the first dielectric layer portion 396 a and the second dielectric layer portion 396 b may be formed as mirror images of each other and disposed adjacent to each other, separated by a parting line 396 c, which may be formed as a gap between the first dielectric layer portion 396 a and the second dielectric layer portion 396 b. The first dielectric layer portion 396 a and the second dielectric layer portion 396 b may be housed between the upper manifold portion 380 a and the lower manifold portion 308 b, as shown in FIG. 9B . As described above, the presence of the parting line 396 (i.e., the gap between the first dielectric layer portion 396 a and the second dielectric layer portion 396 b) can alleviate thermal stress / strain due to mismatches between the CTEs of the dielectric layer 396, the upper manifold portion 380 a, and the lower manifold portion 308 b.

[0076] Each of the first and second dielectric layer portions 396a and 396b includes a hole 1004a, 1004b, which may include the upper portions of the lower inlet hole 384A and the lower outlet hole 384B. Thus, an electrically insulating cloth 1008 including a second hole 1004s is disposed between the first and second electrically insulating shims 1002a and 1002b, such that the first, second, and third holes (1004f, 1004s, 1004t) are aligned to form a continuous hole (e.g., 1004a or 1004b) in an assembly (e.g., the first or second portion of the insulating layer 396).

[0077] Figure 11 is a cross-sectional view of the manifold plate 380 of Figure 9A taken along line L5 shown in Figure 9A, in accordance with various embodiments. As shown in Figure 11, the manifold plate 380 may include a dielectric layer 396 having a first dielectric layer portion 396a sandwiched between an upper manifold portion 380a and a lower manifold portion 308b. The remaining structural details of the manifold plate 380 are similar to those described above with reference to Figure 7B.

[0078] Figure 12A is a vertical cross-sectional view of a fuel flow structure similar to that of Figure 8A including the manifold plate 380 of Figures 9A and 9B, according to various embodiments. In this example, the cross-section is along line L5 in Figure 9A. As shown, the fluid flow structure includes a first dielectric layer portion 396a sandwiched between an upper manifold portion 380a and a lower manifold portion 380b. The remaining structural details of the fuel flow structure of Figure 12A are similar to those described above with reference to Figure 8A.

[0079] Figure 12B is a vertical cross-sectional view of the fuel flow structure of Figure 12A taken along line L6 shown in Figure 9A, according to various embodiments. As shown, the fluid flow structure includes a second dielectric layer portion 396b sandwiched between an upper manifold portion 380a and a lower manifold portion 308b. The remaining structural details of the fuel flow structure of Figure 12B are similar to those described above with reference to Figure 8B.

[0080] While various embodiments of solid oxide fuel cell interconnects, end plates, electrolytes, and manifold plates have been described above, each embodiment may include any other fuel cell component, such as a molten carbonate, phosphoric acid, or PEM fuel cell electrolyte, interconnect, or end plate, or any other form of metal or metal alloy, or compressed metal powder, or ceramic object not associated with a fuel cell system.

[0081] The foregoing description has been provided merely as an illustrative example and is not intended to require or imply that the operations of the various embodiments must be performed in the order presented. As one of ordinary skill in the art would understand, the order of operations of the foregoing embodiments may be performed in any order. Words such as "then," "next," and "next" are not necessarily intended to limit the order of operations, but rather these words may be used to guide the reader through the method description. Furthermore, references to singular elements in the claims, using, for example, the articles "a," "an," or "the," should not be construed as limiting the element to the singular. Furthermore, any operation or component of any embodiment described herein may be used in any other embodiment.

[0082] The above description of the disclosed aspects is provided to enable any person skilled in the art to make and / or use the disclosed embodiments. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Thus, the embodiments of the present disclosure are not intended to be limited to the aspects shown herein but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. A manifold plate for a fuel cell stack, comprising: The lower manifold part, An upper manifold portion; a dielectric layer sandwiched between the lower manifold portion and the upper manifold portion; a lower inlet hole and a lower outlet hole formed in a lower surface of the lower manifold portion and extending through the dielectric layer; an upper outlet hole and an upper inlet hole formed on opposite sides of an upper surface of the upper manifold portion; an outlet passage fluidly connecting the upper outlet aperture to the lower inlet aperture; an inlet passage fluidly connecting the upper inlet aperture to the lower outlet aperture; and The dielectric layer is a first dielectric layer portion; a second dielectric layer portion; the first dielectric layer portion and the second dielectric layer portion are separated by a gap formed between the first dielectric layer portion and the second dielectric layer portion. Manifold plate.

2. The manifold plate of claim 1 , wherein the first dielectric layer portion and the second dielectric layer portion are mirror images of each other.

3. 3. The manifold plate of claim 2, wherein the first dielectric layer portion and the second dielectric layer portion are disposed adjacent to each other and in a common plane.

4. A manifold plate for a fuel cell stack, comprising: The lower manifold part, An upper manifold portion; a dielectric layer sandwiched between the lower manifold portion and the upper manifold portion; The dielectric layer is a first dielectric layer portion; a second dielectric layer portion; The first dielectric layer portion and the second dielectric layer portion each include: a first electrically insulating shim; a second electrically insulating shim; an electrical insulating cloth sandwiched between the first electrical insulating shim and the second electrical insulating shim; The manifold plate has a multilayer structure including:

5. 5. The manifold plate of claim 4, wherein the first dielectric layer portion and the second dielectric layer portion each further include an insulating seal sandwiched between the lower manifold portion and the upper manifold portion.

6. 6. The manifold plate of claim 5, wherein each insulating seal comprises a glass or glass-ceramic annular seal surrounding each hole in the dielectric layer.

7. The manifold plate of claim 4 , wherein the first electrically insulating shim and the second electrically insulating shim each comprise a ceramic material.

8. The manifold plate of claim 7 , wherein the first electrically insulating shim and the second electrically insulating shim each comprise alumina.

9. The manifold plate of claim 4 , wherein the electrically insulating cloth comprises fiberglass.

10. 2. The manifold plate of claim 1, wherein the gap formed between the first dielectric layer portion and the second dielectric layer portion is configured to relieve thermal stress and thermal strain due to a mismatch in the thermal expansion coefficient of the dielectric layer relative to the thermal expansion coefficients of the lower manifold portion and the upper manifold portion.

11. 1. A fuel cell stack fuel flow structure comprising: a base plate having an inlet hole and an outlet hole; a first dielectric layer disposed on the base plate and having an inlet hole and an outlet hole; a cover plate disposed on the first dielectric layer and having an inlet hole and an outlet hole; a seal plate disposed on the cover plate and having an inlet hole and an outlet hole; a manifold plate disposed on the seal plate; and The manifold plate includes: The lower manifold part, An upper manifold portion; a second dielectric layer sandwiched between the lower manifold portion and the upper manifold portion; a lower inlet hole and a lower outlet hole formed in a lower surface of the lower manifold portion and extending through the second dielectric layer; an upper outlet hole and an upper inlet hole formed on opposite sides of an upper surface of the upper manifold portion; an outlet passage fluidly connecting the upper outlet aperture to the lower inlet aperture; an inlet passage fluidly connecting the upper inlet aperture to the lower outlet aperture; 1. A fuel cell stack fuel flow structure comprising:

12. the inlet holes in the base plate, the first dielectric layer, the cover plate, the seal plate, the lower manifold section, the second dielectric layer, and the upper manifold section are aligned to form an inlet conduit passage, and the outlet holes in the base plate, the first dielectric layer, the cover plate, the seal plate, the lower manifold section, the second dielectric layer, and the upper manifold section are aligned to form an outlet conduit passage; or the inlet holes in the base plate, the cover plate, the seal plate, and the manifold plate are aligned to form an inlet conduit passage, and the outlet holes in the base plate, the cover plate, the seal plate, and the manifold plate are aligned to form an outlet conduit passage; 12. The fuel cell stack fuel flow structure of claim 11.

13. A fuel cell stack, 12. The fuel cell stack fuel flow structure of claim 11; an interconnect stacked above the fuel cell stack fuel flow structure; a fuel cell disposed between the interconnects; and A fuel cell stack comprising:

14. the fuel cell includes a solid oxide fuel cell; the upper outlet hole is fluidly connected to a fuel inlet of the interconnect; the upper inlet hole is fluidly connected to a fuel outlet of the interconnect; The fuel cell stack of claim 13.

15. 1. A method of manufacturing a manifold plate for a fuel cell stack, comprising: providing a lower manifold portion and an upper manifold portion; providing a dielectric layer; assembling the lower manifold section, the upper manifold section, and the dielectric layer into the manifold plate so as to sandwich the dielectric layer between the lower manifold section and the upper manifold section; Including, The step of providing a dielectric layer comprises: providing a first electrically insulating shim including a first hole; providing a second electrically insulating shim including a third hole; disposing an electrically insulating cloth including a second hole between the first electrically insulating shim and the second electrically insulating shim, thereby forming an assembly in which the first hole, the second hole, and the third hole are aligned with one another; The method includes:

16. providing an electrically insulating seal between the lower manifold portion and the upper manifold portion such that the electrically insulating seal surrounds the second hole; sintering the assembly under a mechanical load; 16. The method of claim 15, further comprising:

17. The method of claim 15 further comprising the step of placing a fuel cell stack on the manifold plate.

18. A method of manufacturing a manifold plate for a fuel cell stack, comprising: providing a lower manifold portion and an upper manifold portion; providing a dielectric layer; assembling the lower manifold section, the upper manifold section, and the dielectric layer into the manifold plate so as to sandwich the dielectric layer between the lower manifold section and the upper manifold section; Including, the dielectric layer has a first dielectric layer portion and a second dielectric layer portion; the first dielectric layer portion and the second dielectric layer portion are separated by a gap formed between the first dielectric layer portion and the second dielectric layer portion; The method, wherein the first dielectric layer portion and the second dielectric layer portion are disposed adjacent to each other and in a common plane.

19. The method of claim 17, further comprising the step of positioning a fuel cell stack on the manifold plate.

20. A fuel cell stack comprising: a fuel cell stack fuel flow structure; an interconnect stacked above the fuel cell stack fuel flow structure; a fuel cell disposed between the interconnects; and and The fuel cell stack fuel flow structure comprises: a base plate having an inlet hole and an outlet hole; a first dielectric layer disposed on the base plate and having an inlet hole and an outlet hole; a cover plate disposed on the first dielectric layer and having an inlet hole and an outlet hole; a seal plate disposed on the cover plate and having an inlet hole and an outlet hole; a manifold plate according to claim 4 disposed on said seal plate; A fuel cell stack comprising:

21. A fuel cell stack comprising: a fuel cell stack fuel flow structure; an interconnect stacked above the fuel cell stack fuel flow structure; a fuel cell disposed between the interconnects; and and The fuel cell stack fuel flow structure comprises: a base plate having a fuel inlet passage and a fuel outlet passage; a manifold plate disposed on the base plate; a fuel inlet conduit inserted into the fuel inlet conduit passage; a fuel outlet conduit inserted into the fuel outlet conduit passage; The manifold plate includes: The lower manifold part, An upper manifold portion; a dielectric layer sandwiched between the lower manifold portion and the upper manifold portion.

Images